Lobing system



April 8, 1958 Filed oct. 5, 19.45

R. H. DIcKIE LOBING SYSTEM 2 Sheets-Sheet 1 I FIGBB FIGBC I7 2IEIA-B+c-DI I6 f f I5 Juf BALANCED I.F.

l -K MIXER AMPLIFIER l I b [C l a IuIA+cIIe+Dn 5j 4 .6 I5 i 1 |5 7?)31 l1?"1/8 9 'E585' IO Il c d. I2 b al c d r TO'E" a c I 36 35 5 Jd L o. 2o

- Ie Isp 22 (#500) TCR. BALANCED I.F.

'2 f MIXER AMPLIFIER IacA++c+D 22s5 BALANCED I.F. R.IA+B+C+DI MIXERAMPLIFIER W20 2e Ia,IIA+BI-Ic+n 7 l 2e\ 7 f2s, l-Q BALANCED I.. BALANCED.MIXER 29/ MAGIC "T" \3O MIXER VIDEO 33 I 3 2 vIDEo AMPLIFIER AMPLIFIERELEvA'rIoN AzIMuTI-I FIG A ERROR SIGNAL ERROR SIGNAL b l F|G.3 i @um dITI 7)- l0 /Pm I3 a F\G.3A Io /Is 9 DEJE/40 INVENTOR ROBERT H. DICKEATTORNEY April 8, 1958 R. H. DIcKE 2,830,288

LOBING SYSTEM Filed oct. 5. 1945 2 sheets-sheet 2 FIG.4

21 I7 FIGE) 22 H 2 2 AMPLIFIER MI'xER MIXER AMPLIFIER T RtA-B) b 4 gws:cad --Io' I2' IIIA+B al RIA-BI ngc-D) TRANSMITTER aa ncA+B c+D /IaAMPLIFIER MIXER \osclI'I( JE-IFOR 257 l a' 26) BALANcED' R, A+B+c+mR,IA+B+C+D BALANCED MIXER AzIMUTI-I ERROR 27' ELEvATIoN MIXER l SIGNAL yERROR SIGNAL 9' 4o 'II' Io' II' Io' 9' 4o II' Io' INVENTOR ROBERT H.DICKE I2' BY 'n ATTO R NE "I associated motors.

2,830,288` LoBlNG SYSTEM i Robert H.`Dic'ke, Cambridge, Mass.,`assignor,by mesne assignments, `to'tlie United States of America as representedbythe Secretary of the Navy' .t

A, My present invention Yrelates to directional radio an- 2,830,288VItfalented Apr. 8, 195e tem;

tennas and inparticular to s uch `antennas that yield ind of theantenna,` as for keeping the antenna pointed at a desired transmitter or` target. 1

In radio communication. between two directive .radio stations `orpin`radar systemsyit 'Si-ten: desirable to have `an antenna system` which isdirectional and which fur- `ther hasmeans for indicating wh nthe antennais pointed directly at the 4other station or atthe desired target.` Suchsystems as have been-usedy in Ltlie past have. involved mechanicallobe-switehirigyor systematic antenna scanning, such as conical canningor other types of beam e scanning. All of thesepast systems arecharacterized. by

a necessity for moving mechanical parts, such as` rotating antennaconiigurations or rotating. capacitor devices, and

` fIt is a specific object of my present invention` toprovide adirective radio .antennawhich `will perform, the func-` tion of a lobeswitched or conical scanning or other type ofdirectional antenna ofthecharacter being discussed without the use of any moving parts.Accordingly, my

present invention contemplates aradio system which may be either areceiver system or a radarsystem as desired,

`having an antenna system comprising a plurality orfantennaelementswhichmay be so fed that together these elements produce a single directivebeam for transmitting. In receiving, the signals received by theaforementioned individual antenna elements are separated and then re-Vcombined in a novel fashion to produceldirectional error signals in atleast two planes,`such as, for example, ver.- tical and horizontalplanes, as well as a reference signal from the main beam. These signalsare then further combined to produce direct current directional errorimpulses `whichinay be used to actuate visual directional error devicesVor automatic directional error corrective devices.

It is another object of myeinvention to provide sucha directive `radiosystem that' will eliminate spurious signals that tend to provide falseerror signals.

i It is a still further object of my invention to provide such a systemin which the local oscillator of the detector `formation that aids inmaintainingthetrue direction Y Fig. 1A illustrates one. type of duplexbalancer that may be used in thev apparatus oil-iig. 1;

` Fig. 2 illustrates .an arrangement of antenna elements that maybeusedwith the apparatus of Fig. 1;

Fig. 3 isa cross section along the line III-III in Fig." 2; Figs. 3A to3D inclusive illustrate various conditions of. electrical phasing-thatmayV exist' in thel antennas of Fig; 2 whenlth'osef antennasV arereceiving radio signals; `1?ig.4 illustrates thejcharacter of thetransmission beam produced by the. antenna of Fig. 2;

` Fig. 5. illustratesv a second embodiment of my invention in electricalschematic form;

Fig. .6, illustrates, an arrangementof Vantenna elements that; maybeused withk the Vapparatus of'Fig. 5; e Eig. 7 is; a cross sectiontaken along'the line VII- VII inFig.. 6; and i Figs'. 7A t o-7;Dinclusiveillustrate the various electrical phase coniigurations: thatmay exist :inthe antennas of Fig, 6 when theseV antennas are receivingradio signals.

. Althoughmy invention may. be illustrated more simply in aradioreceivingsystemthe apparatus of-`Fig. l shows the invention as embodiedin a radar system, inasmuch as the function of receivingisincludedinsuch systems. Accordingly, a radio transmitter 1 is provided connectedto a transmission line; The energy generated by the transmitter 1 isledthrough the transmission line 2 to a first for generating the errorsignal is operative only when a received signal is in the antennasystem.

It is another object of myinventioni to provide adirective biplanarsimultaneous lobe comparison antenna system which will provide bethYazimuth and elevation error signals without the use of any moving part.

It is a still further` object of my invention to provide adirectiyebiplanar simultaneous lobe comparison antenna system for aradar system which may be used for both transmitting and receiving andwill provide both azimuth and elevation error signals without the use ofany moving parts. Y q

These and other Objectsof my invention may be more `fully understoodfrom a careful consideration of the following detailed description. whentaken together with thev junction of four transmission 'lines a, I2, c,and d, known as a duplex balancer,; illustrated `schematically in abloclci.v For-a better; understanding of the invention, the duplexbalancer Will; be now explained iny greater detail.

The blocks 3, 4,` 5,; 6, 7 and, 8 inclusive each illustrate a .duplexbalancer, disclosed, and'so-namedin the co'- pending` application ofWarren A. Tyrrell for Coupling Arrangementsrfor Use in4 WaveTransmission Systems, Serial No. 470,810., -led December 31, 1942, nowPatent No. 2,445,895, dated- July 27, 1948, and assigned to Bell Telephone Laboratories, Inc. `The duplex 4balancer is a. systemcomprising a common junction of four or morev transmission. lines,I a;b,- c, and d, with each other or .with a fifth line. If the system ismatched to eliminate resonance in the variouslines for the energy 'beingcarried therein, the electrical struct-,ure andA symmetry ofthe sys-Vtemmay be so arranged that the following characteristics are` had, amongothers:- e

' (l.) Power fed into line a; passes into lines c and d in equalquantities, emerging from c and din the same phase, no power passingintoline l?. Y

(V2) Power fed into lines and d in phase enters line a, but not line b.A

(3) Power fed into lines c andgd in phase opposition enters line b butno t line a.

(4) Power fed into line cor d entersv lines a and I n but not theremaining line d or c.

Such a matched arrangement is more specificallyV termed a` Magic Teefandis described in great" detail in my o wn copending. application forTransmission Systems," Serial No. 58l,69,5.iiled, March 8, 1945, nowPatent No. 2,593,120, dated April 15,- 1952, assigned to the UnitedStates Government, wherein eertainlmatching means for a Magic Teeconstructed of waveguides are disclosed. The aboveenumerated"characteristics are employed in my present invention as' willhereinafter Akbe mare rfully explained. 1 I e Although a duplex balancermay be made of any desired type of transmission line, or of circuitelements, as discussed and shown in the aforementioned copendingapplication of Tyrrell, only that form constructed entirely of waveguides, as for. example, that illustrated in.Fig. 1A, will be consideredherein, inasmuch asthe embodiments of my invention herein describedillustrate the invention as it may be practiced usingwave guidesv fortransmission lines. When any brancha, b, C, or d of any Magic Tee is notbeing used, that branch should preferably be terminated in an impedancethat will avoid reflections of energy therein, such as thecharacteristic impedance of the branch. Accordingly in Fig. 1, theterminations 1S are preferably characteristic impedances for thebranches b of theMagic Tee in which they are -installed. s.

Referring now to Figs. 1 to 4 inclusive, energy entering the vfirst linea of the first Magic Tee 3 will in accordance with the above discussiondivide andv pass into the third and fourth lines c and d of this MagicTee inV equal quantities and in like phase. No energy will enter thesecond line b. Thereafter the energy in the third line-c will proceedinto the rst line a of the second Magic Tee 4,

assesses f The portions of energy A, B, C, and D received by the antennaelements 9, 10, 11 and 12 respectively are returned to the Magic Tees 4and 6 respectively through the respective third and fourth lines c and dthereof. Considering now the second Magic Tee 4, for example, theinphase components of the portions A and B of the energy in the thirdand fourth lines c and d thereof combine in the fashion A+B and enterthe first line a thereof, while the oppositely phased components of saidportions A and B combine in the fashion A-B and enter the second line bthereof. Likewise, yin the third Magic Tee 6,y the inphase components ofthe portions C and` D of energy returned to this Magis Teecombine in thefashion C+D and enter the first line a thereof, while the oppositelyphased components of said portions C and D combine in the fashion C-Dand enter the second line b thereof.

` Thus in the second lines b of the second and third Magic and againwill divide and leave this second Magic Tee 4 in equal quantities andlike phase through the third and fourth lines c and d, respectively,thereof. Likewise,- Vthe energy from the fourth line d of the firstMagic Tee 3 will enter the first line a of the third Magic Tee 6 anddivide and leave thatA Magic Tee through the third and fourth lines cand d, respectively, thereof in equal quantities and like phase. Fromthe third and fourth line, c and d, respectively, of the second andthird Magic Tees 4 and 6 respectively, the energy will then pass to fourantenna elements 9, 10, 11 and 12 which are thereunto connected bysuitable transmission lines.

These antenna elements 9, 10, 11 and 12 are preferably symmetricallyarranged around a point 13 and are fed with equal signals of like phasefrom the second and third Magic Tees 4 and 6, respectively. As a result,a single lobe 14 of energy is produced by the four antenna elements 9 to12 inclusive together, this lobe having an axis Z-Z passing through thepoint 13. From one aspect, the four antenna elements 9 to 12 inclusivecomprise two vertically aligned pairs of antennas 9 and 11, and 10 and12, and from another aspect they comprise two horizontally aligned pairsof antennas 9 and 10,l and 11 and 12, respectively. A vertically alignedpair, 9 and 11, is illustratedalone in Fig. 4 to simplify thediscussion. Thus for transmission purposes, the energy generated by thetransmitter 1 is emitted by the combined antennas 9 to 12 inclusive as asingle directive beam 14. For reception purposes, however, it isconvenient to think of the energyin each antenna element 9, 10, 11 and12 as a separate portion of the received energy and to consider theindividual phases of these portions. Each antenna element 9, 10, 11 and12 receives an individual portion A, B, C, or D respectively of theenergy reflected back into the antenna from a target T thatmay be in thebeam 14. The portions received by the antenna elements each have theirindividual phase with respect to each of the others. Thus, for example,when the target T lies on the axis Z-Z, the distances L and L' to eachantenna element 9 and 11 respectively are the same, and the portions ofenergy A and` C respectively received in these elements will have thesame phase. However, when the target T is at T the distances M and M tothe antenna elements 9 and 11, respectively, are different, Vand theportions of energy A aud C respectively received in these antennas willhave different phases with respect to each other which are resolvableinto two pairs of components, havlng respectively like and oppositephases. Similarly, as will be hereinafter explained in greater detail,an olfaxis position of the target T in a horizontal plane will result 1noppositely phased pairs of components 0f th 911 ergy in other pairs ofantennas. 'i i A Tees 4 and 6 respectively, two first parts A-B and C-Dofthe returned signal will be had, while in the first lines a ofthesevMagic Tees, two second parts Afl-B and C+D of the returned signalwill be had. v .l

The two first parts A-B and C-A-D of the returned signal are brought toa fourth MagicvTee 5 through the third and fourth line c and d thereof,Theinphasevcomf ponents of thesetwo first parts Ae-B` `and C-D` combinein the first line a of the fourth Magic Tee 5, and provide a firstdirectional error signal k(A -B-lC-D), where k isa constant ofproportionality, A matching termination 1,15 is provided for the lsecond line bof the fourth Magic Tee 5, for the'purpose of absorbing anysignal havinghthe yalue k(A-vB-(,C-D)), the reason fory which will4 behereinafter explained.`

Returning now to the two second parts A+B and C-l-D of the returnedsignal present inthe first lines` a of the second and third Magic Tees 4and 6 respectively, these two second parts combine in the first MagicTee 3, entering therein through the third and fourth line c and dthereof. The inphase components of these two second parts A-'I-B andC-l-D combine in the first line a to form a directional reference signalk(A-|Bl-C+D), which is the only signal that is had when the target Tlies precisely on the axis Z-Z. The oppositely phased components ofthese two second parts A-l-B and C-l-D combine and enter the second lineb of the first Magic T ce 3 .and form a second directional errorv signalk(A-{-B-C-D). The lirstand second directional error signals are inreality azimuth and elevation error .signals respectively when the`aforementioned pairs of antennas are vvertically and horizontallydisposed, as will hereinafter become apparent. The first and seconddirectionalerror signals and the directional reference signal are eachpassed through respective receiver protective devices, which may be TRboxes 16, and thence to mixers 17, 18, and 19 respectively, preferablyof the balanced mixer type. A common local oscillator 20 is provided forthe mixers 17, 18 and 19,

The local oscillator output is fed to the first line a of a duplexbalancer 8 which is preferably a Magic Tee. In

order that essentially line impedance may be presented to the first arma of the Magic Tee 8 from the local oscillator 20, it is desirable toinclude a matched non-reflective attenuator, as for example theattenuator 35, in the line 38 from the local oscillator to the saidfirst arm a. The attenuator 35 has a strip of absorptive material 36 ona curved surface, and is hinged at a point 37 in such a manner as topermit insertion of the material 36 into the line 38 in varying degreesas desired. The attenuator 35 and other similar suitable attenuators aremore fully described in the copending application of Shepard Roberts,Serial No. 523,885, filed February 25, 1944, now Patent No.v 2,646,551,assigned to the United States Government.

l The signal from the local oscillator divides and inphase inconventional superheterodyne receiver fashion.

5 duplex balancers 3, 4, an'd 6, respectively; The local oscillatorsignal in the third b'ra'nch` 'c of the duplex balancef 8 enters thefirst linea of another duplex balancer 7, which again is preferably aMagic Tee, where further equal division takes place and inphase equalportions of the signal proceed into the third `and fourth lines'` e andd thereof. The signals in these last mentioned linest` 'and d arebrought into the first and second balanced mixers 17 and18 as localoscillator signals. Another portion f the local oscillator power, thatin the fourth line d of the duplex balancer 8 connected to the localoscillator20 of, thus preventing cross-signals .between the first twomixers 17 and 18 or the Magic Tee 7 and the third mixer 19. Suchisolation has the desired 4result of eliminating a possible source ofVfalse error signals. Matchingv terminations are provided for the secondlines b of the two last-mentioned duplex balancers 7 and 8,respectively. A line stretcher 20 is provided in the line E betweenl theduplex balancer 3` and the third balanced mixer 19 in order that theproper phase may be had between the two directional error signals andthe directional reference signal in operations hereinafter occurring. Y

In order that the apparatus may be 'better understood, it is appropiratethat the nature of a balanced mixer be discussed briefly. The balancedmixer is a device for accomplishing the usual functions of a mixer withthe addition of the following desirable characteristics:

(l) The local oscillator signal alone, even when modulated, does notcause the mixer to produce an output voltage; thus signals such Vasnoise arriving at the mixer with the local oscillator powerare notconverted.

(2) There must be an input signal to the mixer in addition to localoscillator power before Athe mixer will produce an output signal.

My copending application for Electrical Systems, Serial No. 584,226,filed March 22, 1945, now Patent No. 2,547,378, disclosesV balancedmixer circuits having the above characteristics. y

The output from each balanced mixer 17, 18 `and 19 is fed to an I. F.amplifier 21, 22 and 23, respectively,

output of the first I. F. amplifier 2l is k1(A-B+C-D), where k1 is asecond constant of proportionality. This is the I. F. of the first`directional error signal, and is fed to a fourth balanced mixer 25 forthe purpose of detection. The output k1(A-|B-C-D) of the second l. F.amplifier 22, which is now the intermediate frequency of the seconddirectional error signal, is fed to a `fifth balanced mixer 26 for thepurposes of detection of that signal. The output k1(A -l-B-l-C-l-D) ofthe third I.` F. amplifier 23 is used in the fashion of a localoscillator voltage for the two last mentioned -balanced mixers 25 and26, and is fed to an electrical circuit 27 which functions preferably inthe manner-of a matched duplex balancer or Magic Tee. Thus the signalfrom the last mentioned I. F. amplifier 23 enters the circuit 27 at afirst point 28 and is evenly divided and proceeds in like phase out ofthird `and fourth points29 and 30. From these points 29 and 30, thesignals are-fed tothe fourth and `fifth balanced mixers 25 and 26 as.the local oscillator signals therefor. No power enters the matchingimpedance 3l. This Magic Tee 27 may be constructed in the fashion of aconventional hybrid coil las knownin the art of telephony. The textbookCom- 1rrmnmatior1 Engineering by W. L. Everitt (McGraw,

The

, Thus, if, for example, the fourth balanced mixer :25 is not perfectlybalanced and feeds some stray signal 'back into Vthe Magic Tee 27through its fourth Vterminal .point 30, thisV signal will be splitbetween the first and second terminal points 2S and 30. Then, becausethese ter'minals are further terminated byrtheir characteristicimpedances (the third amplifier 23 and the matched inipedance 31 beingthereto respectively matched to avoid the reflection of energy), thissignal islcompletely ab'- sorbed and none is transferred to the thirdterminal point 29 or the fifth balanced mixer 26. Y"

The directional reference signal k1(A-|-B+C-.|D)

' from the third I. F. amplifier 23 and the two 'error slignalsk1(A-Bl-C-D) and k1(A+`B-C--D) from the first and second I. F. ampliers2l and 22, respectively,

are all of the same frequency, so that the outputs of the` lastmentioned balanced mixers 25 and 26 will have` but one component each,namely a modulated direct cul"- rent or video pulse. These D. C.signalsV will each be proportional in magnitude to the respectiveassociated directional error signal, and will be zero when that signalis zero. The video outputs are fed to video amplifiers 32 and 33,respectively, which amplifythese video signals and provide first andsecond directional eiror signals, respectively, which may be used forvisual indi cation or automatic control devices in manners known to theart. l

The operation of the apparatus hereinabove discussed will now beexplained in Vgreater detail. Referring to Fig. 4, it will'be recalledthat when the target T is off the axis Z--Z the distance from 'thetarget M and M will be greater for one antenna element 9 than for an'-other 11 in the same plane. This will be true for any pair of antennaelements lying in a plane in which the target is off axis. Thus theportions A and C of the energy reliected to the antenna elements 9 and1l, for example, will have components having like and different phasesupon entering thesertwo antenna elements. As illustrated in Figs. 3A to3D inclusive, various phase configurations of the reflected Venergy inthe antennas 9 to 12 inclusive may be had for various positions of thetarget T with respect to the axis Z-Z of the beam 14. Thus in Fig. 3A,the on-target condition (i. e. ta'get on the axis Z-Z) is illustrated,all components of the portions A, B, C, and D of reflected energy beingin phase, as shown by the `arrows 40 in all four antennas 9, 10, 11, and12. In Fig. 3B, the arrows 40 and 41 illustrate the phase configurationof components of the incoming signals A, B, C, and D which is had whenthere is azimuth error in the target position or in the training of theantenna. This configuration may be 'represented as (A-l-C)(B{D), whichis algebraically identical to A-B-l-C-D, and yields the first errorsignal k(A-B+C-D). In Fig. 3C elevation error is illustrated, as thearrows 40 and 41 show that the top pair 9 and 10 of the antenna elementshave components ,of the portions A+B in one phase while the bottom pair11 and 12 of the antennas have componnets of the portions C-l-D'ofreflected energy in the opposite phase. This may be represented as (A-l-B)-(C}D), whichis algebraically identical to (A-l-B-C-D) and Ayieldsthe second error signal k(A-{B-CD). The condition illustrated in Fig. 3Dis the condition for an undesired mode of oscillation in the antennaelements, 9 to 12, in-

, 7 The configurations illustrated in Figs. 3A, 3B and 3C provide thedirectional reference signal, the azimuth or rst error signal and theelevation or second error signal, respectively. As can be readilyappreciated, no moving mechanical parts are required to produce thesesignals.

In Figs. 5, 6, 7, and 7A to 7D inclusive, there is illustrated anotherembodiment of my invention which, al-

though somewhat simpler than the embodiment of Figs.

l' to 4 inclusive, has similar features. The transmitter 1 feeds into afirst duplex balancer 3 through a line 2. The second line b of thisduplex balancer 3 is terminated in a matching impedance i since thisline is not used. Equal quantities of energy generated by thetransmitter 1 are fed in like phase to the third and fourth arms c and dof this rst duplex balancer 3, and enter the first arms a of the secondand third duplex balancers 4 and 6, respectively. This power againdivides in each of the last mentioned duplex balancers, leaving them inequal quantities and like phase through the third and fourth arms c andd respectively thereof and passing to four antenna elements 9', 10', 11and 12', respectively. These antenna elements function in the samemanner as the antenna elements 9 to 12 inclusive of the apparatus ofFigs. 1 to 4 inclusive, Ybut are somewhat differently arranged. It isthis difference in antenna arrangement that make possible the simplifiedapparatus of Figs. 5 to 7 inclusive. As illustrated in Figs. 6 and 7,two of the antenna elements 9 and 10 are arranged in a hori- `zontalpair on each side of a point in space, i3, while the remaining twoantennas 11 and 12 are arranged in a single Vertical pair, so that wehave now only one horizontal and one vertical pair. The four antennas 9to 12 inclusive being fed in phase and with equal quantities of energy,a single lobe of energy wi-ll be produced on transmission, similar tothe lobe 14 of Fig. 4.

i From Figs. 7A to 7D inclusive, it is apparent that energy returnedfrom a target on the axis of the antenna system will have only inphasecomponents of the portions A, B, C and D of received energy (Fig. 7A),an azimuth error will yield an oppositely phased set of components ofthe portions A and B (Fig. 7B), and an elevation error will yieldoppositely phased components of the portions C and D (Fig. 7C).Returning energy will again have the inphase component of the portionsA, B, C and D thereof added in the iirst arm a of a firstA duplexbalancer 3 to produce a reference signal k'(A-{B{Ci-D), which is thenpassed to a mixer 19 and ampliiier 23 to produce a proportionate signalk1(A-|B-{C-{D). The oppositely phased components of the portions ofreturned energy A and B present in the horizontal pair of antennas 9 and19 will leave the second duplex balancer 4 through the second arm bthereof, and pass through a mixer 17 and an amplifier 21 to provide asignal k1(A -B) proportional to the azimuth error. This signal k1(A-D)is then fed to a balanced mixer 25 as the input signal therefor.Likewise, a signal k(C-D) is provided by the oppositely phasedcomponents of the portions of returned energy C and D, which isproportional to the Vertical or elevation error. This signal k(C-D) isfed to a mixer 18 and amplifier 22, becoming k1(C-D), which is then fedinto a balanced mixer 26 as the input signal therefor. The referencesignal r1(A-{-B+C[D) is provided to the balanced mixers 25 and 26through a junction 27 as a local oscillator signal, similarly to theapparatus of Fig. 1. A common local oscillator 12 feeds through ajunction 8 to the tirst three mixers 17, 18, and 19. The junction S may,if desired, be a duplex balancer or Magic Tee rather than a simplejunction as illustrated in Fig. 5. Likewise, the junction 27 throughwhich the reference signal k1(A-{-Bi-C+D) is brought to the balancedmixers 25 and 26 may be of the matched hybrid coil type of Fig. 1. Theoutputs of the balanced mixers 25 and 26 are again modulated D. C. orvideo signals proportional respectively to the azimuth and elevationerrors. Thus it can be seen that the apparatus of Figs. 5 to 7 inclusivefunctions in a manner similar to the apparatus of Fig. 1, but in asimpliiied form.

Since certain changes may be made in the above described article anddifferent embodiments of the invention could be made without departingfrom the scope thereof, it is intended that all matter contained in theabove description as shown in the accompanying drawing shall beinterpreted as illustrative and not in a limiting sense. For example,the antenna systems illustrated are only two examples of adaptablesystems. A parabolic or other type of reector could if desired be addedand the illustrated antennas might be so located as to illuminate suchreflector. If the invention be embodied in an apparatus intended tooperate at a frequency too low to permit the economical use of waveguide transmission lines, other types of lines, duplex balancers andantenna elements proper for the operative frequency may be used withoutdeparting from the invention. Accordingly it is intended that theinvention be limited only as required by the prior art and the spirit ofthe appended claims.

What is claimed is:

1. A directive radio receiving system comprising, a plurality ofindividual antennas arranged about a line in space for simultaneouslyreceiving individual portions of the radiation from a particular sourcethereof, each of said individual portions being resolvable into inphasecomponents and oppositely phased components, said antennas beingarranged in a plurality of pairs at least one of which has its membersdisposed vertically one above and one below said line and at least oneother of which has its members disposed horizontally one on each side ofsaid line, means for producing a first signal proportional to theinphase components of all of said portions, means for producing a secondsignal proportional to the difference between the oppositely phasecomponents of those of said portions received by said verticallydisposed pairs of antennas, means for producing a third signalproportional to the difference between the oppositely phased componentsof those of said portions received by said horizontally disposed pairsof antennas, and means for producing first and second direct currentoutput signals proportional to said second and third signalsrespectively.

2.' Apparatus in accordance with claim l in which said direct currentproducing means comprises, first and second balanced mixers, and meansfor providing said first signal in like phase and substantially equalquantities to each of said mixers as a local oscillator signal, saidsecond and third signals being brought one to each of said mixers as theinput signal therefor, whereby said local oscillator signal is presentonly when input signals are present in said mixers.

3. An object detecting system comprising, means for generating radioenergy, an antenna for directively radiating said energy in a beam andfor directively receiving reflected energy from objects in the path ofsaid beam, said antenna comprising four radiating elements arrangedsymmetrically about the axis of said beam in one or more vertically andone or more horizontally disposed pairs, each of said pairs having itsmembers located on opposite sides of said axis, means for feeding allfour of said radiators in the same phase from said generating means,said antenna being thereby adapted to radiate said energy in a singlebeam, said antenna being further adapted simultaneously to receive aseparate portion of said reflected energy in each of said elements, eachseparate portion being resolvable into an inphase component and anoppositely phased component, means for producing a first signalproportional to the inphase components of all of said portions, meansfor producing a second signal proportional to the difference between theoppositely phased components of those of said portions received by saidvertically disposed pairs of antennas,

9 means for producing a thi d4 signal proportional to the differencebetween the oppositely phased components of those of said portionsreceived by said horizontally disposed pairs of antennas, and means forproducing first and second direct current output signals proportional tosaid second and third signals respectively. i

4. An `object detecting system comprising, means for generating radioenergy, a first four line duplex balancer connectedat its first line tothe output of saidmeans in such fashion that said energy divides evenlyand proceeds in the same phase into the third and fourth lines and noneof said energy enters the second line thereof, second and third similarduplex balancers connected at their respective first lines to said thirdand fourth lines respectively of said first duplex balancer in likefashion so that said energy proceeds in equal quantities and like phaseinto the third and fourth lines and none into the second lines thereof,four antennas connected one to each of said third and fourth lines ofsaid second and third duplex balancers, said antennas beingsymmetricallyarranged about a point in space, the two antennas connectedto said second duplex balancer being horizontally disposed evenly abovesaid point and the remaining two antennas being horizontally disposeddirectly below said first two antennas, said antennas forming from oneaspect two horizontal pairs and from another aspect two vertical pairsof antennas, said antennas being fed with equal amounts of said energyin like phase and producing a directive beam of said energy having anaxis passing through said point, said antennas being each adaptedsimultaneously to receive individual portions of that amount of saidenergy that may be refiected'to them by an object lying in said beam,and delivering said ret liected energy `to said second and third duplexbalancers through their respective third and fourth lines, the inphasecomponents of said portions present in said third and fourth lines ofeach of said second and third duplex balancers combining and enteringtherespective first lines and the oppositely phased components of saidportions combining and entering the respective second lines of saidsecond and third duplex balancers to form second and first parts of saidreflected energy respectively,` a fourth similar duplex balancerconnected at its third and fourth lines to said second lines of saidsecond and third duplex balancers respectively, said first parts of saidreflected energy present in said second lines of said second and thirdduplex balancers entering said fourth duplex balancer through saidsecond and third lines thereof and the inphase components of said firstparts combining in the first line thereof to form a rst directionalerror signal, the oppositely phased components of said first` partscombining and entering the second line of said fourth duplex balancer, amatched termination for said second line, the second parts of saidreflected energy entering said first duplex balancer through the thirdand fourth lines thereof and the oppositely phased components of lsaidsecond parts combining in the second line of said first duplex balancerto form a second directional error signal, the inphase components ofsaid second parts combining in the first line of said first duplexbalancer to forma direction reference signal.

p 5. An object detecting system comprising, means for generating radioenergy, a first four line duplex balancer connected at its first line tothe output of said means in such fashion that said energy divides evenlyand proceeds in the same phase into the third and fourth lines and noneof said energy'enters the second line thereof, second and third similarduplex balancers connected at their first lines to said third and fourthlines respectively of said first duplex balancer in like fashion so thatsaid energy proceeds in equal quantities and like phase into the thirdand fourth lines and none into the second lines thereof, four antennasconnected one to each of said third and fourth lines of said second andthird duplex balancers, said antennas being symmetrically arrangedentering the respective first lines and the oppositedly' asaoass aboutra point in space, the two antennas connectedto said second duplexbalancer being horizontally disposed one on each side of said point andthe remaining twor antennas being vertically disposed respectivelyabovev and below said point, said antennas being fed with equal amountsof said energy in'like phase and producing ai directive beam Vof saidenergy having an axis passingV through said point, said antennas beingeach adapted to' receive individual portions of that amount of saidenergy that may be reflected to them by an object lying in said beam,and delivering said reflected energy to said second and third duplexbalancers through their respective third and fourth lines, the inphasecomponents of said portions present in said third and fourth lines ofeach of said second and third` duplex balancers combining and phasedcomponents of said portions combining and entering the respective secondlines of said second and third duplex balancers, the respectiveresulting signals present in said last mentioned second lines beingfirst and second directional error signals, the resulting signals due tosaid reflected energy present in said last mentioned first linesentering said first duplex balancer through its third and fourth lines,the inphase components of said last mentioned signal combining in thefirst line of said first duplex balancer to form a direction referencesignal, and a matched impedance termination for the second line of saidfirst duplex balancer.

6. A directive radio system Vcomprising a transmitter, a firstvertically spaced pair of antennas and a second horizontally spaced pairof antennas, a first network coupled to said transmitter for dividingthe signal from said transmitter into first and second components whichare in phase with each other, second and third networks coupled to saidfirst network, said second network dividing said first component intothird and fourth components in phase with each other, said third networkdividing said second component into fifth and sixth components in phasewith each other and in phase with said third and fourth components,means coupling said third and fourth components to the first and secondantennas respectively of said vertically spaced pair, meansv couplingsaid fifth and sixth 4components to the first and second antennasrespectively of said horizontally spaced pair, said two pairs ofantennas being arranged to transmit the signal in a concentrated beamand to receive energy reflected from an object within said beam, saidsecond network being further adapted to resolve the signal received bysaid first antenna of said vertical pair into seventh and eighthcomponents respectively and to resolve said signal from said secondantenna of said vertical pair into ninth and tenth componentsrespectively, said seventh and ninth components being in phaseopposition and said eighth and tenth components being in phase with eachother, said second network providing a first output signal to said firstnetwork proportional to the vector sum of said eighth and tenthcomponents and a second output signal proportional to the vectordifference of said seventh and ninth components, said third networkbeing further adapted to resolve the signal from said first antenna ofsaid horizontal pair into eleventh and twelfthl components respectively,and to resolve the signal received by the second antenna of saidhorizontal pair into thirteenth and fourteenth components respectively,said eleventh and thirteenth components being in phase opposition, saidtwelfth and said fourteenth components being in phase, said thirdnetwork providing a first output signal to said first networkproportional to the vector sum of said twelfth and fourteenth componentsand a second output signal proportional to the vector difference of saideleventh and thirteenth components respectively, said second outputsignals of said second and third networks respectively being indicativeof the position of the source of received energy with respect to saidantennas.

v afname/s 7. A directive radio system as in claim 6 wherein said first,second and third networks are electrically and mechanically passive.

8. A directive radio system as in claim 6 wherein said first networkproduces a first output signal in response to said first output signalsfrom said second and third networks respectively, said system furthercomprising a local oscillator, a first mixer responsive to said secondoutput of said second network and a signal from said local oscillatorfor producing a first intermediate frequency signal, a second mixerresponsive to said second output of said third network and a signal fromsaid local oscillator for producinsr a second intermediate frequencysignal, a third mixer responsive to said first output signal of saidfirst network and a signal from said local oscillator for producing athird intermediate frequency signal, a fourth mixer responsive to saidfirst and third intermediate frequency signals, and a fifth mixerresponsive to said second and third intermediate frequency signals, thcoutput signals of said fourth and fifth signals being indicative of theposition of the source of receiver signals with respect to saidantennas.

9. A directive radio receiving system comprising, first, second, thirdand fourth antennas arranged at the corners of a rectangle, saidantennas being further arranged for simultaneously receiving individualportions of the radiation from a particular source thereof, first meansfor resolving the signal received by said first antenna into first andsecond components each spaced in phase with respect to saidlast-mentioned received signal and for resolving the signal received bysaid second antenna into third and fourth components, sai thirdcomponent being in phase with said first component and said fourthcomponent being in phase opposition to said second component, said firstmeans being further adapted to provide a first output signalproportional to the vector sum of said first and third components andsecond output proportional to the vector difference of said second andfourth components, second means for resolving the signal received bysaid third antenna into fifth and sixth components each spaced in phasewith respect to said last-mentioned received signal and for resolvingthe signal from said fourth antenna into seventh and eighth components,said fifth and seventh components being in phase and said sixth andeighth components being in phase opposition, said second means beingfurther adapted to provide a first Output signal proportional to thevector sum of said fifth and seventh signals and to provide a secondoutput signal proportional to the vector difference of said sixth andeighth components, third means for resolving said first output signal ofsaid first means into ninth and tenth components each spaced in phasewith respect to said first output signal of said first means and forresolving said first output signal of said second means into eleventhand twelfth components said eleventh component being in phase with saidninth component and said twelfth component being in phase opposition tosaid tenth component, said third means further providing a first outputsignal proportional to the vector sum of said ninth and eleventhcomponents and a second output signal proportional to the vectordifference of said tenth and twelfth components, and fourth means forresolving said second output of said first means into thirteenth andfourteenth components each spaced in phase with respect to said secondoutput signal of said first means and for resolving said second outputsignal of said second means into fifteenth and sixteenth components,said fifteenth component being in phase with said thirteenth componentand said sixteenth component being in phase opposition to saidfourteenth component, said fourth 12 means being further adapted toprovide a first output signal proportional to the vector sum of saidthirteenth and fifteenth components, said first output of said fourthmeans and said second output of said third means being indicative of theangular position of said source with rcspect to said antennas.

10. A directive radio receiving system comprising first, second, thirdand fourth antennas arranged at successive corners of a rectangle, saidantennas being further arranged for simultaneously receiving individualportions of the radiation from a particular source thereof, resolvingmeans coupled to said antennas for resolving the signals from each ofsaid antennas into first components each in phase with a reference phaseposition and second components each in phase quadrature with saidreference phase, said resolving means being further adapted to provide afirst output signal proportional to the vector sum of said firstcomponents, a second output signal proportional to the vector sum of thevector difference of said second components of the'signal from saidfirst and second antennas respectively and the vector difference of saidsecond components of the signal from said fourth and third antennas'respectively, and a third output signal proportional to the vectordifference of the vector sum of said second components of the signalsfrom said first and second antennas respectively and the Vector sum ofsaid second components of said signals from said third and fourthantennas respectively.

11. A directive radio receiving system as in claim 10, said systemfurther comprising first, second and third mixer circuits, meanscoupling said first, second and third output signals to said first,second and third mixers respectively, a local oscillator, means couplingsaid local oscillator to said first, second and third mixers wherebysaid first mixer produces a first intermediate frequency signal, saidsecond mixer produces a second intermediate frequency signal and saidthird mixer produces a third intermediate frequency signal, a fourth anda fifth mixer, means coupling said first and second intermediatefrequency signals to said fourth mixer and means coupling said first andsaid third intermediate frequency signals to said fifth mixer, saidfourth and fifth mixers producing first and second error signalsrespectively, said error signals being indicative of the angularposition of said source with respect to said antennas.

12. A directive radio receiving system as in claim 10 wherein saidresolving means comprises a mechanically and electrically passivenetwork.

13. A directive radio receiving system as in claim 10, said systemfurther comprising a transmitter, means coupling said transmitter tosaid resolving means, said resolving means being further adapted tocouple the energy from said transmitter to said four antennas equallyand in phase.

References Cited inthe le. of this patent UNITED STATES PATENTS2,411,034 Gluyas Nov. 12, 1946 2,412,161 Patterson Dec. 3, 19462,416,155 Chubb Feb. 18, 1947 2,423,104 Labin July 1, 1947 2,445,895Tyrrell July 27, 1948 2,480,829 Barrow et al Sept. 6, 1949 2,510,692Goddard June 6, 1950 2,593,120 Dicke Apr. 15, 1952 FOREIGN PATENTS441,964 Great Britain Jan. 30, 1936

